A wide variety of devices are known for spreading and flattening a tubular knit fabric in a circular knitting machine. U.S. Pat. No. 2,553,074 issued to Beard, U.S. Pat. No. 2,652,615 issued to Lasley, and U.S. Pat. No. 3,402,444 issued to Merrill all disclose such devices.
The Beard patent discloses an adjustable tubular fabric spreader formed as a U-shaped frame having a rounded nose or bight portion and a pair of opposed limbs or arms that are generally parallel. The ends of the arms are respectively joined to transversely extending sleeves, which in turn are telescopically slidable in the ends of a main sleeve or handle that forms part of a turnbuckle means. Reinforcing stay rods are connected between the sleeves and the bight portion of the U-shaped frame. Rotation of the handle operates the turnbuckle means and thus permits adjustment in the distance between the ends of the arms, thereby adjusting the width of the spreader. The turnbuckle means for adjusting the width of the spreader is relatively complicated.
The Lasley patent discloses an opening shoe for opening and detwisting a tubular fabric such as is necessary after wet processing of the tubular fabric in rope form so that the fabric can be passed through the nip between a pair of stop rolls. The shoe is formed by plate members presenting flat top and bottom shoe faces, and a tubular frame to which the plate members are secured, so that the tubular frame presents rounded edges. The fabric encloses the shoe and the shoe and fabric tube are supported in a horizontal orientation by a roll and the stop rolls. Thus, the weight of the shoe does not contribute toward fabric tension in Lasley's device. Furthermore, the shoe is of fixed geometry. Lasley's shoe also would have a relatively high center of gravity when used in a vertical position and thus may be prone to instability in a rotating circular knitting machine take-down unit.
The Merrill patent discloses a tubular fabric spreader frame or divider unit disposed within the tubular web for maintaining the web width substantially constant just prior to the passing of the web between a pair of rolls. The divider unit includes a first frame member having a vertical member that extends along the fabric movement direction and has a horizontal hollow sleeve joined perpendicularly to the vertical member at a lower end thereof. A second frame member is formed similarly to the first frame member and has a vertical member and a horizontal member joined to a lower end thereof and configured to be slidably received in the sleeve of the first frame member. A third frame member is resiliently biased with respect to the second frame member and includes a horizontal member slidably disposed within a bracket that is mounted on the vertical member of the second frame member. The width of the divider unit is adjustable by operating a friction latch that is mounted on a pair of horizontal members attached to the first frame member and that engages another horizontal member attached to the second frame member, such that the horizontal member on the second frame member slides relative to the sleeve. The tubular fabric is spread by the first and third frame members, and by virtue of the resilient biasing of the third frame member, the divider unit is said to exert a proper degree of tension to maintain the web at a predetermined width. Merrill's divider unit would have a relatively high center of gravity and thus may be prone to instability when used in a rotating circular knitting machine. Moreover, the divider unit is quite complicated in its construction.